Although synanthropic invasive murid rodents are freely traded in pet shops in South Africa, their taxonomic identities, however, remain largely unknown. Twenty-four murid rodents were sampled from pet shops in four of the five municipalities in Gauteng Province, South Africa for genetic identification using mitochondrial cytochrome b (mtDNA) sequence data. Distance-based Neighbour-Joining (NJ), character-based maximum likelihood (ML) and model-based Bayesian inference (BI) were used to infer the relationship between the pet murid rodents. Brown rats (Rattus norvegicus) and house mice (Mus musculus) were the most dominant species in the pet shops. The results demonstrated that pet shop owners lacked the taxonomic expertise to identify murid rodent species they trade in. For example, the juveniles of brown rats were misidentified as adults of the house mouse. The murid rodents sampled in the current study were genetically affiliated to both wild and laboratory strains of R. norvegicus and M. musculus. The results of the BI showed that the pet murid rodents were in the terminal clades as those of conspecifics in NCBI GenBank reference sequences. The molecular data used in the current study may be useful for developing national policies and regulations for synanthropic invasive murid rodents in the pet trade industry in South Africa.

Although synanthropic rodents such as the indigenous species, Mastomys coucha, and the invasive species, Rattus norvegicus, R. rattus and R. tanezumi, are well-known to be hosts to various micro- and macroparasites, their helminth parasite fauna is poorly studied in South Africa. In an attempt to remedy the situation, the aim of the present study was to investigate the helminth fauna of these sympatric rodent species, which were obtained from the informal settlements of Alexandra, Tembisa, Diepsloot and residential suburbs of Pretoria and Hammanskraal, Gauteng Province, South Africa. Helminths were recovered from the urinary bladder, liver and gastrointestinal tract and were identified morphologically and molecularly. The recovered nematodes were all rodent-specific and included Aspiculuris tetraptera, Eucoleus sp., Heterakis spumosa, Mastophorus muris, Nippostrongylus brasiliensis, Protospirura sp., Strongyloides ratti, Syphacia obvelata, Syphacia muris, Trichuris sp. and Trichosomoides crassicauda. Syphacia obvelata, a commensal nematode of laboratory rodents, was recovered from indigenous M. coucha. Strobilar stages of cestodes recovered included Hymenolepis diminuta, Hymenolepis nana and Inermicapsifer madagascariensis. Recovered metacestodes were strobilocerci of Hydatigera taeniaeformis from all three invasive Rattus species and coenurostrobilocerci of Hydatigera parva from M. coucha. An acanthocephalan, Moniliformis moniliformis, was recovered from R. rattus only. All rodent species examined showed high helminth infection prevalence (≥70%) with equal or higher nematode than cestode prevalence. Mastomys coucha, however, showed significantly lower cestode prevalence than Rattus species where they co-occur. Interspecific transmission of helminths likely occurs between invasive and indigenous rodents, and these rodents harbour several helminths that have zoonotic implications.

Lack of adequate sanitation and pest control, and poor housing conditions that prevail in much of both rural and urban South Africa, cause rodent populations to thrive, promoting contact with humans, which results in increased risk of zoonotic disease transmission. This study focused on bacterial pathogens involved in potential zoonoses present in 3 commensal and invasive Rattus spp., namely Rattus norvegicus, R. rattus, and R. tanezumi, from rural and urban South Africa. Bacterial prevalence and diversity was determined through amplification and sequencing of the mitochondrial 16S gene region, using 4 primer sets: 2 that have a broad bacterial species recognition range, and 2 genus-specific sets that target the genera Streptococcus and Streptobacillus. An overall bacterial prevalence of 32% (n = 84) in kidney samples was obtained using the 16S universal primer sets. Subsequent sequence analyses found bacterial prevalence per host species to be 41% for R. norvegicus, 42% for R. rattus, and 8% for R. tanezumi, with representatives of diverse bacterial taxa such as Clostridium sordelli (toxic shock syndrome), Bacillus cereus (diarrhoeal disease), and Enterococcus faecalis (nosocomial infections) being characterised. The primer set targeting Streptobacillus moniliformis was used to determine the prevalence of this zoonoticallyimportant bacterial taxon, which is transmissible via a bite from Rattus to humans, whilst Streptococcus-specific primers were used to assess environmental shedding of this agent via the urinary route. The results highlight the public health implications especially for immune-compromised individuals, as these rodent-borne pathogens can cause opportunistic infections that in such individuals are not readily diagnosed or treated.

Three species of Rattus, Norway rat (R. norvergicus), black rat (R. rattus) and Asian house rat (R. tanezumi) are currently known to occur in South Africa. The latter two species are cryptic and form part of the Rattus rattus species complex. Historically, R. norvegicus has been reported to occur along the coast and in urban centres, R. rattus is widespread in most urban areas, except in the drier areas, while R. tanezumi was only recorded to occur in the country (and Africa) ca. 15 years ago, and its distribution remains unknown. The aim of this study was to predict the potential distribution of R. tanezumi in South Africa and assess how it overlaps with that of R. norvegicus and R. rattus using species distribution modelling. Rattus tanezumi was predicted to mainly occur in most inland urban areas and along the coast. The distribution of R. rattus was as expected, in contrast, the predicted range of R. norvegicus was not restricted to the coast but also included inland urban areas. All three species showed broad potential distributional ranges that overlapped extensively indicating that their establishment and spread may be influenced by similar factors such as proximity to urban areas and a wet and moderate climate. These results allow insights into assessing their risk of establishment and for formulating appropriate intervention strategies for their management and control.

Concurrent studies of helminth parasites of introduced and native rodent species are few and miss the opportunity to identify potential co-invasive parasite species. This study employed molecular tools to infer the phylogeny and elucidate the origin of potentially co-invasive parasites of commensal, murid rodents by assessing introduced Rattus norvegicus, Rattus rattus, Rattus tanezumi, and native Mastomys coucha in Gauteng Province, South Africa. Genotypes of Nippostrongylus brasiliensis recovered from R. norvegicus are nearly identical to those recovered from elsewhere in the world. The pinworms, Aspiculurus tetraptera, recovered from introduced R. tanezumi and R. rattus, Syphacia muris recovered from R. tanezumi, and Syphacia obvelata recovered from indigenous M. coucha have affiliations to those recovered of laboratory rodents from the USA and China. Syphacia obvelata was previously only known as a commensal endoparasite of laboratory rodents, and the S. muris genotype recovered from R. tanezumi in this study shows an affiliation to a genotype recovered from the same host species in Indonesia which is part of the native range. The study emphasizes the need for surveillance of potential co-invasive species and contributes in documenting genetic diversity of endoparasites of well-known hosts.

Poor socio-economic and unsanitary conditions are conducive to commensal rodent infestations, and these conditions are widespread in South Africa. Cestode species of zoonotic interest are highly prevalent in commensal rodents, such as invasive Rattus norvegicus, Rattus rattus, Rattus tanezumi, and indigenous Mastomys coucha, and have been frequently recovered from human stool samples. These cestode species have similar transmission dynamics to traditional soil-transmitted helminths (STHs), which ties them to infections associated with poverty and poor sanitation. Univariate analysis was used in the present study to determine the association between rodent-related factors and cestode prevalence, while ecological niche modelling was used to infer the potential distribution of the cestode species in South Africa. Cestode prevalence was found to be associated with older rodents, but it was not significantly associated with sex, and ectoparasite presence. The predicted occurrence for rodent-borne cestodes predominantly coincided with large human settlements, typically associated with significant anthropogenic changes. In addition, cestode parasite occurrence was predicted to include areas both inland and along the coast. This is possibly related to the commensal behaviour of the rodent hosts. The study highlights the rodent-related factors associated with the prevalence of parasites in the host community, as well as the environmental variables associated with parasite infective stages that influence host exposure. The application of geospatial modelling together with univariate analysis to predict and explain rodent-borne parasite prevalence may be useful to inform management strategies for targeted interventions.